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Status of MODIS and VIIRS Instruments

Xiaoxiong (Jack) Xiong

Sciences and Exploration Directorate, NASA Goddard Space Flight CenterGreenbelt, MD 20771, USA

EOS

CERES Science Team Meeting, NASA LaRC, Hampton, VA (April 26-28, 2016)

Acknowledgements:

MODIS Characterization Support Team (MCST)

VIIRS Characterization Support Team (VCST)

Outline

• Introduction

− MODIS and VIIRS Instruments

− Calibration Approaches

• MODIS and S-NPP VIIRS On-orbit Performance

• MODIS L1B and S-NPP VIIRS SDR (L1B)

• Summary

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3

Introduction

• MODIS on Terra and Aqua Missions

– Terra: Dec. 18, 1999 – Present

– Aqua: May 04, 2002 – Present

• VIIRS on S-NPP and JPSS Missions

– S-NPP: Oct. 28, 2011 – Present

– JPSS-1: launch in Jan 2017

– JPSS-2: launch in July 2021 CERES

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SDSM

Scan

Mirror

Solar

Diffuser

SRCA

Blackbody

Space

View

SD/SDSM:Weekly to tri-weekly

SRCA:Radiometric: monthlySpatial: bi-monthlySpectral: quarterly

Moon: monthly (nighttime orbits)0-20o spacecraft roll maneuvers55o phase angle

BB: quarterly

Spacecraft maneuvers:Yaw (SD BRF, VF)Roll (Moon)Pitch (only applied to Terra)

MODIS On-orbit Calibration Methodologies

VIIRS operation/calibration strategies are similar to MODIS (no SRCA in VIIRS)

Terra and Aqua MODIS On-orbit Performance

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• SD degradation: wavelength-dependent (larger at shorter wavelength; faster with more solar exposure)

• BB stability: excellent (more stable in Aqua)

• Changes in detector responses– Large changes in VIS and NIR (strong wavelength and AOI dependent)

– Small changes in SWIR, MWIR, and LWIR

• Changes in responses versus scan-angle (RVS): RSB only

• Changes in polarization characteristics (primarily in Terra VIS bands): science impact

• Spatial and spectral: stable through entire missions

• Terra safe hold event (2/18/16)– Nominal operation resumed

– Additional noisy detectors (21 of the 26 noisy detectors since launch are in LWIR PV bands; 11 of the 21 occurred after safe hold event)

S-NPP VIIRS On-orbit Performance

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• SD degradation: similar to Terra MODIS

• BB stability: similar to Aqua MODIS

• Changes in detector responses– Large changes in NIR and SWIR (due to mirror contamination)

– Small changes in VIS, MWIR, and LWIR

• Changes in responses versus scan-angle (RVS): small– Monitored using EV data at different AOI

• Spatial performance: stable through entire mission– Tracked using lunar observations (no SRCA)

• Spectral performance: modulated RSR– VIIRS unique feature

– Mirror contamination => wavelength dependent optics degradation

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Aqua MODIS VIS/NIR Radiometric Responses

Similar l, AOI, and mirror side dependence for Terra MODIS VIS and NIR responses

SD View (AOI=50.2⁰) SV View (AOI=11.2⁰)

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MODIS SWIR, MWIR, and LWIR Radiometric Responses

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MODIS VIS/NIR Spatial Characterization Performance

CFPA CFPA

Terra BBR: within spec (±0.1 km) for all band pairs (except for along scan B30 and B32)

Aqua BBR: a known issue since pre-launch

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MODIS VIS/NIR Spectral Characterization Performance

CW and BW changes are within 0.5 nm and 1.0 nm, respectively, for most VIS/NIR bands

Relatively large changes are observed for bands with broad bandwidths (bands 1, 18, 19)

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MODIS and VIIRS show similar wavelength dependent SD degradation • Terra MODIS: SD door kept at open since 2003 (1999-present)• Aqua MODIS: SD door opens only during SD/SDM calibration (2002-present)• S-NPP VIIRS: no SD door (2011 to present)

MODIS and VIIRS SD Degradation

SD degradation monitored by the on-board SDSM

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VIIRS RSB Spectral Band Responses (from SD calibration)

SD and lunar calibration at the same AOI

Small difference between SD and lunar calibration observed for a few bands

SD long-term trends normalized to lunar trends in latest calibration LUTs

Large changes in NIR/SWIR responses due to telescope mirror degradation on-orbit modulated RSR

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VIIRS TEB Spectral Band Responses (from BB calibration)

Excellent stability: less than 0.5-1% over 4+ years (similar to Aqua MODIS)

MODIS has more TEB with wavelengths up to 14.5 mm

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l dependent optics degradation led to Modulated RSR

DNB

Small impact on bands with narrow bandwidths and small OOB responses; large impact on DNB (broad bandwidth)

DNB

S-NPP VIIRS On-orbit Modulated RSR

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Status of MODIS Level 1B Data Products (C6)

• Collection 6 (C6) L1B products released to public July 2012 for Aqua and Nov 2012 for Terra

• C6 L1B data can be downloaded from:

http://ladsweb.nascom.nasa.gov/

• New improvements since C6 release

Correction applied to reduce Terra B5 (and potentially other SWIR bands) long-term drift as SDSM can only track SD degradation in VIS and NIR region

Forward updates of Aqua TEB nonlinear calibration coefficient (a2)

Improved use of default gains for bands 33, 34, and 36 during BB WUCD

More bands included the earth view trending at different AOIs for RVS characterization (Terra band 10 added; Aqua bands 1-4 pending science team approval)

Polarization corrected trending for RVS characterization (under science evaluation by land team)

Terra PV LWIR electronic crosstalk correction (pending science team review)

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• Land SIPS SDR reprocess using IDPS Code with VCST LUTs (C1.0 and C1.1)– IDPS SDR/EDR codes Mx based version with LUTs input from VCST

– 35 sets of LUTs for RSB (and DNB) have been delivered to Land SIPS for data

reprocessing and SDR/EDR assessments in Collections 1.0 and 1.1.

• Atmosphere SIPS SDR reprocess using IDPS Code with VCST LUTs– Mission data reprocessing VIIRS SDR/EDR using Mx8.4 software in late 2014.

– 9 sets of LUTs based on Mx8.4 code format have been delivered (Nov 2014 –

Feb 2016) - same quality LUTs as those sent to Land C1.1.

Status of S-NPP VIIRS SDR (NASA SIPS Support)

Collection Code base # of LUTs Delivery Time (year.month) Improvements

Mx6.3 5 2012.10 - 2013.01Smoothed functions for SD degradation H-

factor and calibration coefficients F-factor.

Mx6.4 5 2013.04 - 2013.11Updated SD/SDSM screen transmission, SD

BRDF, RTA mirrors degradation model, and

modulated RSRs.

C1.1 Mx7.2 25 2013.12 - 2016.02Improved time-dependent modulated RSR,

DNB stray light correction, H & F fitting

functions.

C1.0

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• NASA SIPS L1B/LUTs for mission reprocess (V1.1.0)

– VIIRS L1A and L1B software/LUT and data design are developed under NASA

EDOS/SIPS.

– SNPP VIIRS L0 data as the input for L1A software => 6-min L1A HDF5 data.

– L1A and L1B calibration LUTs are the input for L1B software => Geolocation

and L1B products including OBC.

– First L1B software V1.1.0 was released in Jan 2016 for SIPS evaluation.

– LUTs generations are based on corrected solar vector (error fix), on-orbit

SD/SDSM screen transmission & SD BRDF, modulated RSR, and consistent

fitting of mission data.

Collection Code base # of LUTs Delivery Time (year.month) Note

V1.1.0 L1B V1.1.0 2 2016.02 - 2016.03Redesigned L1B software and LUTs format

using input from NASA L1A data. L1B

products are under evaluation.

Status of S-NPP VIIRS L1B (NASA SIPS Support)

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Status of JPSS-1 VIIRS Calibration and Characterization

Pre-launch Calibration and Characterization:• Sensor level testing

Ambient: 08/24/2013 - 01/19/2014

Pre-TVAC: 05/16/2014 - 07/16/2014

TVAC: 07/16/2014 - 10/30/2014

Post-TVAC: 11/24/2014 - 12/15/2014 (PSR completed in Feb 2015)

• Observatory level testing:

TVAC testing: June, 2016

Preparation for On-orbit Calibration (led by NOAA SDR team)• LUTs development for SDR processing

“at launch” quality LUTs delivered in Dec 2015 (except for a few DNB LUTs to be developed after SC TVAC testing)

Launch in Jan 2017• Intensive calibration and validation (ICV)

• NASA effort similar to S-NPP VIIRS (TBR) – Impact to CERES?

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Status of JPSS-2 VIIRS Calibration and Characterization

Sensor Pre-launch Calibration and Characterization:• Ambient Test Readiness Review (TRR): 03/24/2016

• Ambient phase: April-June 2016 (Started April 6th)

• Key performance testing: RVS, NFR, SLR, SNR, Crosstalk, Polarization, RSR

• Thermal vacuum: February-August 2017

• Key performance testing: Radiometric calibration, SNR, RSR, stability

• Pre-Ship Review (PSR): October 2017

Launch in July 2021

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Summary

• Both Terra and Aqua MODIS continue to operate normally with all on-board calibrators capable of performing their design functions

• Changes in sensor responses (radiometric, spatial, and spectral) have been regularly monitored and corrections have been made to maintain data quality (via calibration LUTs – reprocessing/forward updates)

• Key challenging issues (RVS, polarization, crosstalk, noisy detectors) identified and characterized and mitigation plans developed for future improvements (C6 and beyond)

• S-NPP VIIRS overall performance has been satisfactory (mirror contamination induced optical degradation has significantly leveled off; modulated RSR derived and applied)

• Dedicated effort by VCST has been made in support of NASA PEATE/SIPS for generating consistent and research quality SDR/L1B and EDR

• J1 VIIRS SDR and EDR support for CERES needs to be addressed

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POC:− MODIS and VIIRS: Jack Xiong <xiaoxiong.xiong-1@nasa.gov>

− MODIS: Amit Angal <amit.angal@ssaihq.com>

− VIIRS (S-NPP) Vincent Chiang <kwofu.chiang@ssaihq.com>

− VIIRS (JPSS) Hassan Oudrari <hassan.oudrari-1@nasa.gov>

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Backup Slides

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Key Design Requirements of MODIS Spectral Bands

Primary Use BandBandwidth

(nm)

Spectral

Radiance1

Required

SNRPrimary Use Band Bandwidth (mm)

Spectral

Radiance1

Required

NEDT(K)

1 620 - 670 21.8 128 20 3.660 - 3.840 0.45 (300K) 0.05

2 841 - 876 24.7 201 21 3.929 - 3.989 2.38 (335K) 0.2

3 459 - 479 35.3 243 22 3.929 - 3.989 0.67 (300K) 0.07

4 545 - 565 29 228 23 4.020 - 4.080 0.79 (300K) 0.07

5 1230 - 1250 5.4 74 24 4.433 - 4.498 0.17 (250K) 0.25

6 1628 - 1652 7.3 275 25 4.482 - 4.549 0.59 (275K) 0.25

7 2105 - 2155 1 110 26 1.360 - 1.390 6 150 (SNR)

8 405 - 420 44.9 880 27 6.535 - 6.895 1.16 (240K) 0.25

9 438 - 448 41.9 838 28 7.175 - 7.475 2.18 (250K) 0.25

10 483 - 493 32.1 802 Cloud Properties 29 8.400 - 8.700 9.58 (300K) 0.05

11 526 - 536 27.9 754 Ozone 30 9.580 - 9.880 3.69 (250K) 0.25

12 546 - 556 21 750 31 10.780 - 11.280 9.55 (300K) 0.05

13 662 - 672 9.5 910 32 11.770 - 12.270 8.94 (300K) 0.05

14 673 - 683 8.7 1087 33 13.185 - 13.485 4.52 (260K) 0.25

15 743 - 753 10.2 586 34 13.485 - 13.785 3.76 (250K) 0.25

16 862 - 877 6.2 516 35 13.785 - 14.085 3.11 (240K) 0.25

17 890 - 920 10 167 36 14.085 - 14.385 2.08 (220K) 0.35

18 931 - 941 3.6 57

19 915 - 965 15 250

Atmospheric Water

Vapor 1

Spectral Radiance values are (W/m2-µm-sr)

Land/Cloud/Aerosols

BoundariesSurface/Cloud

Temperature

Land/Cloud/Aerosols

Properties Atmospheric

Temperature

Cirrus Clouds Water

Vapor

Ocean Color/

Phytoplankton/

BiogeochemistrySurface/Cloud

Temperature

Cloud Top Altitude

20 reflective solar bands (RSB) and 16 thermal emissive bands (TEB)

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VIIRS (and MODIS) Spectral Bands

VIIRS Band Spectral Range (um) Nadir HSR (m) MODIS Band(s) Range HSR

DNB 0.500 - 0.900

M1 0.402 - 0.422 750 8 0.405 - 0.420 1000

M2 0.436 - 0.454 750 9 0.438 - 0.448 1000

M3 0.478 - 0.498 750 3 100.459 - 0.479

0.483 - 0.493

500

1000

M4 0.545 - 0.565 750 4 or 120.545 - 0.565

0.546 - 0.556

500

1000

I1 0.600 - 0.680 375 1 0.620 - 0.670 250

M5 0.662 - 0.682 750 13 or 140.662 - 0.672

0.673 - 0.683

1000

1000

M6 0.739 - 0.754 750 15 0.743 - 0.753 1000

I2 0.846 - 0.885 375 2 0.841 - 0.876 250

M7 0.846 - 0.885 75016 or 2

0.862 - 0.877

0.841 - 0.876

1000

250

M8 1.230 - 1.250 750 5 SAME 500

M9 1.371 - 1.386 750 26 1.360 - 1.390 1000

I3 1.580 - 1.640 375 6 1.628 - 1.652 500

M10 1.580 - 1.640 750 6 1.628 - 1.652 500

M11 2.225 - 2.275 750 7 2.105 - 2.155 500

I4 3.550 - 3.930 375 20 3.660 - 3.840 1000

M12 3.660 - 3.840 750 20 SAME 1000

M13 3.973 - 4.128 750 21 or 22 3.929 - 3.989

3.929 - 3.989

1000

1000

M14 8.400 - 8.700 750 29 SAME 1000

M15 10.263 - 11.263 750 31 10.780 - 11.280 1000

I5 10.500 - 12.400 375 31 or 3210.780 - 11.280

11.770 - 12.270

1000

1000

M16 11.538 - 12.488 750 32 11.770 - 12.270 1000

VIIRS MODIS Substitute

1 DNB: L/M/HG32 Agg. Modes

14 RSB:0.41-2.3 mm

7 TEB:3.7-12.1 mm

7 DGB:

M1-M5, M7, and M13

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Rotating Telescope Aft Optics and HAM

Solar Diffuser

Stability Monitor

Extended SV Port

Blackbody

VIIRS on-orbit operation and calibration are based

on the experience and lessons from MODIS

VIIRS On-orbit Calibration Methodologies